SGSH and mucopolysaccharidosis: The prevalent S66W or R245H heparan sulfate sulfamidase (SGSH) mutations in type IIIA MPS reduce mutant enzyme concentrations in the lysosome, most likely due to impaired folding and ERAD in lieu of efficient folding and trafficking of sulfamidase, leading to the accumulation of heparan sulfate and severe CNS degeneration [27].